I'm attempting to make the following replacement in java
@Test public void testReplace(){ String str = "1JU3C_2.27.CBT"; String find = "(\\d*)\\.(\\d*)"; String replace = "$1,$2"; String modified = str.replaceAll(find, replace); System.out.println(modified); assertEquals("1JU3C_2,27.CBT", modified); //fails } However both full stops seem to be getting replaced. I'm looking at replacing only the numeric decimal. (i.e expecting output 1JU3C_2,27.CBT)
Use (\\d+)\\.(\\d+) instead of (\\d*)\\.(\\d*).
Your regex asks to replace zero or more digits followed by a dot, followed by zero or more digits. So . in .CBT is matched as it has a dot with zero digits on both sides.
1JU3C_2.27.CBT has two dots with zero or more digits on both sides.
If you want to convert string like 5.67.8 to 5,67,8 use lazy matching as (\\d+?)\\.(\\d+?).
*
stands for zero or more times, try replacing it with
+
Instead do this:
public void testReplace() { String str = "1JU3C_2.27.CBT"; String modified = str.replaceFirst("[.]", ","); System.out.println(modified); assertEquals("1JU3C_2,27.CBT", modified); } 
